From: Robert Love <rml@tech9.net>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: samson swanson <intellectcrew@yahoo.com>, linux-kernel@vger.kernel.org
Subject: Re: Compiling 2.2.19 with -O3 flag
Date: 24 May 2002 08:19:03 -0700 [thread overview]
Message-ID: <1022253543.962.236.camel@sinai> (raw)
In-Reply-To: <E17BGGw-0006NO-00@the-village.bc.nu>
On Fri, 2002-05-24 at 07:42, Alan Cox wrote:
> Bench it and see. From my own experience -O3 made the kernel a lot larger
> and reduced overall performance - in part because the kernel already
> explicitly figures out what it wants inlined.
>
> Interestingly enough -Os outperformed -O2
Heh, now that is interesting.
Or maybe not - not too long ago I did some tests of the various
optimization options in gcc 2.96 or so and found that -O2 generates
smaller code in most cases than -Os. -Os also did not perform as good,
but I was just testing a few bits of code - nothing as versatile as the
kernel.
The end result was I recommend -O2 for both performance and size. Maybe
I should retest against the kernel...
Robert Love
next prev parent reply other threads:[~2002-05-24 15:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-24 6:51 Compiling 2.2.19 with -O3 flag samson swanson
2002-05-24 14:42 ` Alan Cox
2002-05-24 15:19 ` Robert Love [this message]
2002-05-24 15:44 ` Alan Cox
2002-05-24 16:45 ` Marcus Meissner
2002-05-24 16:54 ` Robert Love
2002-05-24 17:44 ` Christoph Hellwig
2002-05-24 17:55 ` Robert Love
2002-05-24 18:00 ` Christoph Hellwig
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